where can i buy a check valve at? it goes under the throttle body and is connected to this green little filter looking thing mine split apart and i can't find it on mazdatrix it's like a little air filter right next to the intake pipe

 

not quite sure what you mean, do you have any pictures of it? if it's a stock part just start looking in junkyards

 

What colour is it ? Does it attach to the throttle body or just vac lines ?